jsonschema fails to validate patternProperties with additionalProperties=False

[michael-robbins]

Having this weird issue, not sure if I'm just misunderstanding the usage, or if it's a bug?

It looks like setting additionalProperties to False doesn't understand patternProperties and validation fails?

>>> jsonschema.validate(
...   {"a": "a", "b": "a"},
...   schema={
...     "$schema": "http://json-schema.org/draft-07/schema#",
...     "required": ["a"],
...     "properties": {
...       "a": {"type": "string"},
...       "patternProperties": {"b": {"type": "string"}}
...     },
...     "additionalProperties": False
...   }
... )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "~/venv/lib/python3.9/site-packages/jsonschema/validators.py", line 776, in validate
    raise error
jsonschema.exceptions.ValidationError: Additional properties are not allowed ('b' was unexpected)

Failed validating 'additionalProperties' in schema:
    {'$schema': 'http://json-schema.org/draft-07/schema#',
     'additionalProperties': False,
     'properties': {'a': {'type': 'string'},
                    'patternProperties': {'b': {'type': 'string'}}},
     'required': ['a', 'b']}

On instance:
    {'a': 'a', 'b': 'a'}

[michael-robbins]

fml ok ignore me, patternProperties should be set at the 'top level' not within properties